Today, the left side on my old L555 deluxe stopped working on the left side. I've taken off the kick plate, and I can see that the hydraulic motor turns corresponding to the stick. So- it is something in the drive to the wheels. I had to drag it about 30 feet today to get it out of the way. My son worked the right stick and I pulled it from the left side with a backhoe. The left side wheels were not turning- they skidded along in the mud. It is currently in a muddy field. I'm assuming it is going to be something I'll want to do in a clean environment. I guess step 1 is to take off the small inspection plate on the top and see what is happening. Now, I admit I have been very remiss about keeping up with adjustments to chain slack, like the book says. Is it possible that the chain got sloppy and fell off the sprocket inside, or is a break more likely?